Screw & Plug fixing

[sargan]

Apologies if this is a bit long .... looking for some advice on plug & screw fixing.
I have a large quantity of raised garden beds ... so effectively a 100 wide brick wall.
I will be fixing 5mm plastic spacers to maintain an airgap (keep wood off brick) ......
end result will be: http://tinyurl.com/zfxjsar

On advice here decided to use 152 x 7.5 concrete fixing screws http://tinyurl.com/z9g7scr
I will counterbore holes so I can glue in wood plugs ... intend using router to do this.

There are 2 approaches ...
Fixing option A http://tinyurl.com/zzkvu2u
where screws go in at 90 degree, would mean I need a jig of some sort to match angle of sloped section.

Fixing option B http://tinyurl.com/hrmgkkr
Or I simply dill in at 90 degree to surface of angled section - meaning fixing will be angled.
This may give a better fixing, and would mean no jig needed router would go flat on sloped section.

Welcome thoughts on this.

Secondly .......
Screw is 11.1mm across head ......... so need to counter bore to 12mm (or 1/2")
Option would be to use either a screw digger: http://tinyurl.com/zxeef7h
with plug cutte:r http://tinyurl.com/jm8qv65 concern is only tool steel, and more than 200 plugs to cut.
not sure if these would be any better: http://tinyurl.com/jjb8jnz

[tusses]

I didn't click on all your links .. but this might be useful

http://www.plugitdowel.co.uk/wood-produ ... rain-plugs

[tusses]

and this ...

[sargan]

That looks like a cheaper version of the TCT one I gave in the link
with plug cutte: http://tinyurl.com/jm8qv65

[tusses]

my main point was how cheap you can buy plugs ,, rather than cut your own

[sargan]

agree ... just need to confirm the way forward for treated wood ......... if it works I'll buy them.
Saves cost of 1/2" cutting tool as well

[tusses]

or you could use coach screws and make a "feature" of the fixings ?

[sargan]

No - the method of fixing has been decided and screws already purchased.

An option is whether a single screw on centreline of brick ... every 600mm may be 'enough'

[7sheds]

For future reference, have you been introduced to the wonders of 'Thunderbolts' http://www.toolgurus.co.uk/thunderbolt-masonry-anchor/?V44335&gclid=Cj0KEQjwt763BRDZx_Xg3-Pv2cABEiQAoDfeGKMMnQcZs3GSSyqZTJrzvzv1jyuPiBdguZvWn2JRHs4aAtJW8P8HAQ'?